Automatic blood pressure measurement: the oscillometric waveform shape is a potential contributor to differences between oscillometric and auscultatory pressure measurements.

Objective: To explore the differences between oscillometric and auscultatory measurements.

Method: From a simulator evaluation of a non-invasive blood pressure (NIBP) device regenerating 242 oscillometric blood pressure waveforms from 124 subjects, 10 waveforms were selected based on the differences between the NIBP (oscillometric) and auscultatory pressure measurements. Two waveforms were selected for each of five criteria: systolic over and underestimation; diastolic over and underestimation; and close agreement for both systolic and diastolic pressures.

Effect of the shapes of the oscillometric pulse amplitude envelopes and their characteristic ratios on the differences between auscultatory and oscillometric blood pressure measurements.

Introduction: Oscillometric noninvasive blood pressure (NIBP) devices determine pressure by analysing the oscillometric waveform using empirical algorithms. Many algorithms analyse the waveform by calculating the systolic and diastolic characteristic ratios, which are the amplitudes of the oscillometric pulses in the cuff at, respectively, the systolic and diastolic pressures, divided by the peak pulse amplitude. A database of oscillometric waveforms was used to study the influences of the characteristic ratios on the differences between auscultatory and oscillometric measurements.

Validation of oscillometric noninvasive blood pressure measurement devices using simulators.

Oscillometric noninvasive blood pressure devices measure blood pressure using an indirect method and proprietary algorithms and hence require validation in clinical trials. Clinical trials are, however, expensive and give contradictory results, and validated devices are not accurate in all patient groups. Simulators that regenerate oscillometric waveforms promise an alternative to clinical trials provided they include sufficient physiological and pathological oscillometric waveforms.

Can a simulator that regenerates physiological waveforms evaluate oscillometric non-invasive blood pressure devices?

Introduction: A simulator has been developed that enables previously recorded clinical oscillometric waveforms to be regenerated for testing oscillometric non-invasive blood pressure measurement devices. Two non-invasive blood pressure devices were evaluated using the simulator with its database of 243 waveforms, to assess the value of a simulator for such evaluations.

Methods: Two oscillometric non-invasive blood pressure devices, both of which had previously been validated against auscultatory references, were selected.

Characterization of the Korotkoff sounds using joint time-frequency analysis.

The sounds associated with the five classical Korotkoff phases are clinically important for measuring systolic and diastolic blood pressures. The frequency ranges of the sounds have already been described simply using the overall peak frequencies within each phase by Fourier methods. However, such analysis may be missing potentially useful clinical information.